Re: Representation clauses for base-64 encoding

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 11-12-23 03:30 , Randy Brukardt wrote:
> "Niklas Holsti"<niklas.holsti@tidorum.invalid>  wrote in message
> news:9lgi3jFhaU1@mid.individual.net...
>> On 11-12-22 11:41 , Natasha Kerensikova wrote:
> ...
>>>      type Octet_Block is array (1 .. 3) of Octet;
>>>      pragma Pack (Octet_Block);
>>
>> I would add the following, to check that packing is effective:
>>
>>        for Octet_Block'Size use 24;
>
> I think it would probably be better to forget Pack and actually say what you
> mean here:
>
>      type Octet_Block is array (1 .. 3) of Octet;
>      for Octet_Block'Component_Size use 8;
>
> "Pack" should be reserved for cases where you don't care about the exact
> layout, you just want to save space. Here you do care about the exact
> layout, so use a Component_Size.

Fine adjustment: when Component_Size is not a factor or multiple of the 
word size, RM 13.3(73) says that the array may also have to be packed in 
order to eliminate gaps between components.

Of course, a Component_Size of 8 bits is usually a factor of the word 
size. But perhaps not always.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .